Production of H2-rich Syngas from Excavated Landfill Waste through Steam Co-gasification with Biochar

Gasification of excavated landfill waste is one of the promising options to improve the added-value chain during remediation of problematic old landfill sites. Steam gasification is considered as a favorable route to convert landfill waste into H₂-rich syngas. Co-gasification of such a poor quality landfill waste with biochar or biomass would be beneficial to enhance the H₂ concentration in the syngas, as well as to improve the gasification performance. In this work, steam co-gasification of landfill waste with biochar or biomass was carried out in a lab-scale reactor. The effect of the fuel blending ratio was investigated by varying the auxiliary fuel content in the range of 15e35 wt%. Moreover, co-gasification tests were carried out at temperatures between 800 and 1000°C. The results indicate that adding either biomass or biochar enhances the H₂ yield, where the latter accounts for the syngas with the highest H₂ concentration. At 800°C, the addition of 35 wt% biochar can enhance the H₂ concentration from 38 to 54 vol%, and lowering the tar yield from 0.050 to 0.014 g/g-fuel-daf. No apparent synergetic effect was observed in the case of biomass co-gasification, which might cause by the high Si content of landfill waste. In contrast, the H₂ production increases non-linearly with the biochar share in the fuel, which indicates that a significant synergetic effect occurs during co-gasification due to the reforming of tar over biochar. Increasing the temperature of biochar co-gasification from 800 to 1000°C elevates the H₂ concentration, but decreases the H₂/CO ratio and increases the tar yield. Furthermore, the addition of biochar also enhances the gasification efficiency, as indicated by increased values of the energy yield ratio.